Ship derrick mast



March 6, 1951 A. E. HALLEN 2,544,081

SHIP DERRICK MAST Filed Nov. 14, 1946 3 Sheets-Sheet 1 March 6, 1951 A. E. HALLEN SHIP DERRICK MAST 3 Sheets-Sheet 2 Filed Nov. 14, 1946 March 6, 1951 A. E. HALLEN 2,544,081

SHIP DERRICK MAST Filed Nov. 14, 1946 s Sheets-Sheet s wwgw,

Patented Mar. 6, 1951 SHIP DERRICK MAST Alf Eskil Halln, Goteborg, Sweden Application November 14, 1946, Serial No. 709,721 In Sweden November 24, 1945 7 Claims.

The present invention relates to masts and socalled derrick poles which are employed for supporting derricks or other lifting devices on board ships. Masts or poles of this kind have hitherto been constructed in most cases in the form of round tubes which have the same resistance capacity to bending fore and aft and athwartship, and for masts it has usually been necessary to employ stays both in the athwartship and fore and aft direction. Attempts have also been made to use self-supporting masts, that is to say, the masts were constructed with such a large diameter and of such thickness of material that they were capable of carrying the load themselves. Masts of the last-mentioned type are however very heavy and furthermore occupy a relatively large space on the deck in consequence of their large root diameter.

The object of the invention is to produce a mast or pole which is self-supporting in the fore and aft direction, that is to say, which is capable of resisting to the bending stresses occurring in a fore and aft direction without special stays.

This object and further objects are attained by structure illustrated in the accompanying drawings in which: Fig. '1 is a View from fore or aft of two derrick poles arranged side by side on a ship, and a side view thereof is shown in Fig. 2. Fig. 3 is a section to an enlarged scale along the line III-III in Fig. 1, whilst Fig. 4 is a view from above of one of the derrick poles shown in Fig. 1, also to an enlarged scale. Figs. 5 and 6 show a mast construction according to 'the invention viewed from the side and aft, re-

spectively.

Considerable advantages are obtained with a mast or ipole according to the invention in comparison with previous forms of construction. In consequence of the absence of stays acting in a fore and aft direction the derricks have a much greater freedom of movement. For a single derrick polev or mast a single athwartship stay on each side will be found sufiicient, whereas with earlier forms of construction it was necessary to employ at least two stays the fixed points of which at their attachment to the deck were located a considerable distance apart from one another in a fore and aft direction. The arrangement according to the invention thus renders it possible to swing out the derrick substantially at right angles to the side of the ship, whereas it was formerly only possible to obtain an angle of about 60 between the derrick and the fore and aft direction.

By arranging two poles according to the invention so that they are inclined towards one another and connected to one another at the top a form of mast construction is obtained which is self-supporting in the athwartship direction.

The masts or poles according to the invention may suitably taper towards the top. Owing to the construction according to the invention, the lower part of the mast has a relatively large extension in the fore and aft direction, and in the case of tubular masts it is therefore possible to provide ventilating openings in the lower part of the mast for the ventilation of the ships hold and the like. This has not been possible in earlier known forms of construction and it was necessary to carry out ventilation by means of separate Ventilators or through the top of a derrick pole. In order to obtain an adequate cross-section for the air with the last-mentioned form of construction, it was previously necessary to construct derrick poles for this purpose with a relatively large diameter at the top also which entailed an unnecessarily heavy weight. Furthermore, the condensation of the moisture contained in the air inside the long air passage through the pole gave rise to inconvenience.

Owing to the fact that the ventilating openings according to the invention may be located at the lower part of the mast the hollow space in the mast above the ventilating openings may be closed hermetically whereby the inside of the mast will require a minimum of attention. The closure of the inside of the mast may be efiected by means of one or a plurality of intermediate partitions which at the same time strengthen the walls of the tube.

At the ventilating openings are easily accessible they may be provided with closing shutters which may be made adjustable in such a way that in the open position they also serve for controlling the air for the purpose of rendering it possible to produce pressure or suction ventilation in the holds or the like.

In Figs. 1 and 2, numeral I indicates two derrick poles which rise up from a mast housin 3 located on the deck of a ship 2. As will be seen from the figures, the poles also extend below the deck 2 and pass through a space underneath, such as a hold 4. The derrick poles I are narrower towards the top and are connected to one another at the top by a stay 5.

As will be seen from Fig. 3, the cross-section of each derrick :pole in the plane transverse to the longitudinal axis of the pole is an oblong with the major or longer axis extending fore and aft and the minor or shorter axis extending athwartship. As illustrated, each pole of the bipod derrick mast has a substantially oval section and is built-up from two iron plates 6 facing fore and aft, the said plates being connected to one another by Side plates I which are curved outwards. In the example shown, the side plates are of conical form and the derrick pole, viewed from above, will therefore present the appearance illustrated in Fig. 4. From the last-mentioned figure it will also be seen that, as in Fig. 1, the width of the iron plates 6 decreases from the bottom and upwards above the mast housing 3.

In consequence of the oval section and the fact that the thickness of the iron plates 6 is appre ciably greater than the thickness of the side plates 1, the derrick pole will have a much greater rigidity in the fore and aft direction than in the athwartship direction inasmuch as the moment of resistance with respect to an axis parallel to the athwartship direction is greater than the moment of resistance with respect to an axis parallel to the fore and aft direction.

According to Fig. 1, ventilating openings are provided in the sides of each derrick pole immediately above the mast housing, and are covered by shutters 8. The arrangement of these ventilating openings will be seen more clearly from Fig. 3. In this figure, two difierent alternatives are shown, inasmuch as two shutters 8 are indicated diagrammatically in the left-hand porpoles shown in Figs. 1 and 2.

tion of the figure, whilst in the right-hand portion only one shutter is shown. Various adjustable positions for the shutters 8 are shown by dotted lines in the figure. These shutters may be constructed in a known manner in such a way that they can be opened and pivoted as required along the one vertical edge or the other. As the figure shows, it is possible to produce a superatmospheric or subatmospheric pressure in the interior of the pole as required, independently of the direction of the wind. Since the pole communicates through openings 9 below the deck 2 with the holds, pressure or suction ventilation can be obtained in the latter.

A certain weakening of the boom poles is caused by the ventilating openings, which can be compensated in a simple manner by placing Welded frames i0 around the openings.

Above the ventilating openings with the shutters 8, intermediate partitions H are inserted in the poles, being indicated in the figures by dotted lines, and in addition a cover i2 is welded at the top. In this wa hermetically closed spaces are formed in the poles which never require any -maintenance in the form of painting or the like.

The intermediate partitions II also contribute towards the stiffening of the tube construction.

' The derrick poles described above are so di- 'mensioned that they are capable of resisting to the bending stresses occurring in a fore and aft direction without special stays. As the tops are connected to one another by means of the stay 5, the poles together form a construction which is self-supporting in the athwarthship direction also. For practical purposes it is preferable to dimension the poles in such a way that the construction is self-supporting for loads up to 5 to 10 tons for example, whilst for heavier loads which OCCllr less frequently, as for example up to 25 tons, the construction may be strengthened temporarily by the suitable application of stays.

In Figs. 5 and 6, a type of mast construct-ion is shown the lowerpart of which takes the form of a bracket consisting of two poles inclined towards one another and connected at the top, the said poles being of substantially the same construction as those shown in Figs. 1 and 2. The poles l are thus rigidly welded at the top to an outrigger 13 which is intended to serve as the fastenin member for the top rope of the appertaining derrick. As the result of this construction, the mast presents a rigidity in the fore and aft direction which has substantially double the rigidity of each separate pole I, whilst the rigidity in the athwartship direction is sufiicient to en-- able the mast to be self-supporting in this direction at all loads occurring. As may be seen from the figures, the mast construction is accompanied by the same advantages with regard to ventilation as those obtained with the derrick In Figs. 5 and 6 the ame reference numerals have been adopted as in Figs. 1 and 2 to indicate similar constructional elements.

A ships ri carried out according to the invention entails an appreciably lower cost than a corresponding rig of earlier construction and is at the same time much lighter which is a great advantage from the point of view of stability.

The invention is not limited to the forms of construction illustrated and described. The cross-section and mutual location, etc., of the poles or masts can be varied in numerous ways, and poles, masts or the like members constructed according to the invention may replace all forms of previously known derrick poles, masts or the like. The use of the term cross-section here refers not only to the external contour or shape of the section but also to the nature of the parts of the section. Thus for example, the section may be understood to include parts acting as armouring members.

What I claim is:

1. The combination with a ship having a deck and a hold beneath the deck of a bipod derrick mast comprising two tubular pole members extending above and below the deck, said pole members being spaced apart at the base and disposed in a vertical plane extending athwartship, the poles above deck being inclined toward each other and meeting at the top thereof, each of said poles being hollow and oval in cross-section and disposed with the long axis extending fore and aft, each of said poles having ventilating open- .ings in the lower portions thereof above and below decks and a sealing partition closing the interior of said poles to the atmosphere above the upper ventilating opening, means for securing the upper ends of the poles rigidly together and means closing the upper ends thereof.

2. The combination with a decked ship of a biped derrick mast, said mast being substantially self-reinforcing and consisting of two tubular poles disposed in a substantially vertical athwartship plane, said poles being inclined toward and meeting one another at the upper ends thereof, means rigidly interconnecting the upper ends of said poles, the lower portions of said poles extending through at least one deck of said ship and being rigidly connected to the ship structure, and each said pole being oblong in transverse section with the major axis extending substantially fore and aft and being tapered in the upward direction.

3. A ship derrick mast as defined in claim 2 wherein each pole is comprised of fiat iron plates facing fore and aft, and outwardly curved side plates thinner than said fiat plates facing athwartship and connected to said flat plates along the edges so as to constitute a tube of substantially oval cross-section.

4. A ship derrick mast as defined in claim 2 wherein at least one of said poles includes a ventilating opening in one of the wider sides thereof above deck, a transverse partition closing off the interior of said pole above said opening, and a ventilating opening into the pole below deck.

5. A ship derrick mast as defined in claim 4 and which further includes adjustable shutters for the said ventilating opening above deck constructed and arranged to provide superatmospheric or subatmospheric pressure in the pole interior.

6. A ship derrick mast as defined in claim 2 wherein said poles each include a plurality of spaced partitions arranged transverse to the longitudinal axis of the pole and which divide the pole interior into a plurality of scaled compartments.

7. A ship derrick mast as defined in claim 2 and which further includes an outrigger at the junction of said poles extending horizontally athwartship.

'ALF ESKIL HALLEN.

6 REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS OTHER REFERENCES Elements of Yacht Design, by Norman L. Skene,

5 published by Dodd, Mead & 00., New York, 1944,

sixth edition, p. 118. 

